Electrode structure



y 1954 R. ZAPHIROPOULOS j2,683,833

ELECTRODE STRUCTURE Filed Sept. 2, 1952 2 Sheets-Sheet 1 I N V EN TOR. REN/V Z A PH/ROPOUI. 06'

A 7' TOR/VEYS.

y 1954 R. ZAPHIROPQULOS 2,683,833

ELECTRODE STRUCTURE Filed Sept. 2, 1952 2 Sheets-Sheet 2 IN V EN TOR. RE/V/V Z A PH/ROPOUL 0a.

- A TTOR/VEYS.

Patented July 13, 1954 ELECTRODE STRUCTURE Renn Zaphiropoulos, Oakland, Calif., assignor to Chromatic Television Laboratories, Inc., Oakland, Calif., a corporation of California Application September 2, 1952, Serial No. 307,435

13 Claims. (Cl. 31380) The present invention relates to improved types of electrode structure suitable for use, for example in the Direct View Color Tube as set forth in United States patent application of Ernest 0.

Lawrence, Serial No. 234,190, filed on June 29;

1951. Particularly, the invention comprises a multiple strand grid structure supporting, in proximate relation thereto, a target or screen area adapted to be impacted by scanning beam electrons. The application of suitable potentials to the grid and target structures, relative to the electron beam source, enables the grid strands to alter the angle of incidence of the scanning beam and to focus the beam to a substantially linear trace on the target area.

The multiple strands of the grid structure may be maintained at a uniform potential relative to the target, in which case, adjacent strands form electron lenses respectively having their electrical focal points or traces on the target area between the strands. In the alternative a difference of potential may be established between adjacent strands to deflect the electrons of the scanning ray beam or beams (as the case may be) in the direction of the more positive strand with the potential distribution between the strands and the target area also serving to focus the beam into a substantially linear trace Where it impinges on the target area. If the target area is coated with different color light producing phosphors distributed in strips of less than picture-element width, arranged in cyclically repeating arrays, the beam may be caused to impinge upon a strip of any desired color thus effecting color reproduction. Preferably, the phosphor coating is comprised of strips of phosphor capable of producing, upon excitation, primary colors of an additive polychrome system such as, for example, red, blue and green light. Preferably, the transverse dimension of a color cycle of the primary phosphors is substantially equal to the mean diameter of the beam prior to its being focused by the electrode structure of the instant invention. This is also the width between adjacent strands in the electrode structure. Thus, adjacent strands of the grid focus the beam on the target area into a substantially linear trace having a transverse dimension less than the width of the individual phosphor strips.

If the grid conducting strands are oriented to be parallel with the edges of the phosphor strips, the direction of scannin may be either transversely or longitudinally thereof. In either case the beam is focused to a substantially linear trace on any of the selected red, green or blue phosphor areas. The conducting strands are preferably disposed in a substantially coplanar relation and are spaced from the target by means of spacer elements. Optimum spacin of the strands from the target area is dictated primarily by mechanical considerations; the spacing chosen should be as large as is possible while retaining accurate registration with the phosphor strips.

As has been shown, in the Lawrence application above cited, the beam will focus at the plane of the target if the potential of the latter with respect to the cathode, is about 3 times that between the cathode and the grid strands. Then, by additionally app1ying potential of the order of magnitude of one-sixth of that normally on i the grid to alternate strands of the grid, the angle of incidence of the-beam may be altered to the extent necessary to effect a complete color change.

A feature of the present invention resides in the interrelated combination of the elements of the electrode structure to provide accuracy of alinement of the conducting strands with the phosphor coatings on the target area, with only a minimum of distorting stresses prevailing.

Among the objects of the present invention are the following:

To provide an improved deflecting and focusin electrode structure suitable for use in cathode ray tubes; to provide such electrode structure, in combination with a target backing member, capable of accurate and persistent alinement of the multiple conducting strands of the grid; to provide an assembly of the aforementioned nature adapted, upon the application of potential to the target area and grid conducting strands, to alter the angle of incidence of the scanning beam electrons which impact the target; to provide such an electrode structure of rugged character yet interposin a minimum of interception to the infalling cathode rays; and to provide electrode structures admitting of accurate construction at low cost.

Briefly this is accomplished by employing a light-transmissive base plate as the target backing, secured to a grid frame by the strand conductor of the grid. A pair of spacer elements aflixed to one surface of the base plate define a Window or target area therebetween which may be coated with the different phosphor strips necessary to the system to be employed. Insulating means are provided for securing the electrically conducting means or strand conductors to the frame. The electrically conductin means are extended in individual strand fashion, under a certain degree of tension, across the window or target area of the backing and spaced therefrom by the spacer elements. I'he conducting means may be divided into separate sets of alternate strands and suitable means are provided for applying potential to each set of strands. The frame may be divided into two sections with each section serving a separate set of strands in the manner herein set forth, or in the alternative, terminal connections may be made to alternate strands thereby afiording separate sets of strands.

The foregoing will be more apparent from a reading of the following detailed description of the invention when taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a semi-diagrammatic view of a conventional single-gun type cathode ray tube provided with an electrode structure in accordance with the present invention;

Fig. 2 is an elevational view of the target end of the tube of Fig. 1, showing an electrode structure in accordance with the present invention, as viewed from the electron beam source;

Fig. 3 is a cross sectional view of the electrode structure of Fig. 2;

Fig. 4 is a segmental perspective view of a portion of the electrode structure of Figs. 2 and 3, showing the target backing, conducting strands and means of attachment therefore;

Fig. 5 is a reversed perspective view of the segment of Fig. 4;

Fig. 6 is an elevational portion of the target area showing a preferred arrangement of phosphor coatings thereon and grid conducting strands relative thereto;

Fig. 7 shows, in cross section, a portion of a modified type of electrode structure in accordance with the present invention;

Fig. 8 is a bottom view of the structure of Fig.7 as seen along the plane e -3 of Fig. '7, and looking in the direction of the arrows;

Fig. 9 is a view in cross section of a portion of a further embodiment of an electrode structure in accordance with the present invention;

Fig. 10 is a bottom view of the structure of Fig. 9 as seen along the plane ill-4i], and looking in the direction of the arrows; and,

Fig. 11 is a view in perspective of a portion of the electrode structure embodied in the showings of Figs. 9 and 10.

Referring now to the drawings and particular- 1y to Fig. 1 there is shown a conventionally shaped cathode-ray tube having an evacuated envelope 55 within which the electrode structure of the present invention is adapted to be mounted. The neck of the tube includes such conventional elements as an indirectly heated cathode H which acts as the source for a cathode ray scanning beam, indicated by the trace IS, when heated by the filament 2i. Adjacent to and partially surrounding the cathode I? is a control grid or electrode 23 suitably apertured to permit the passage of the electrons comprising the scanning beam. The control grid 23 functions in the usual manner to modulate the emitted stream of electrons in accordance with the potential applied thereto relative to the cathode ll. Also in the neck of the tube there is provided a first anode 25 adapted for the application of suitable potential thereto to provide initial acceleration of the electrons comprising the scanning beam. Adjacent to the first anode there is positioned a second anode 2? for supplying the final acceleration given the electrons in the neck of the tube and also for focusing the scanning beam to a spot, having a diameter substantially equal to one dimension of a picture element, on a target or target backing which comprises a translucent phosphor coated base plate 29.

A set of deflecting plates comprising the usual horizontal pair 3! and vertical pair 33 is provided for conventional scanning purposes. Horizontal and vertical is used herein in a descriptive sense only as the electrode structure of the instant invention is operative with either horizontal or vertical scanning as will be apparent hereinafter. Thus, the scanning beam is caused to scan the target or translucent backing area 29 to produce luminous effects visible through a viewing area 31 of the envelope i5.

The target backing or translucent base plate 29 may be secured in the viewing end of the tube in any of many ways. Fig. 2 shows one way wherein a contoured support ii is adapted to fit within the viewing end of the tube to position securely the base plate 29 in position adjacent the viewing end 31 of the tube. The support 4! is provided with lugs E3 which are shown in Fig. 2 somewhat contoured as the internal periphery of the envelope 15. In the case of a metal envelope l5 small angles may be welded to the inside surface of the envelope at positions where it is desired to attach the lugs 33. The lugs are attached to the angles by means of belts or rivets 41 which pass through ceramic bushings (not shown) and which are provided with insulating discs on each end to isolate electrically the support M from the envelope i5. Obviously, other means of attachment may be employed to secure the support 4! to the envelope 5 with a necessary requirement bei g electrical isolation between these two elements. in similar fashion, ii glass envelopes are to be employed lead-ins may be formed in the envelope and heavy wire supports may be sealed therethrough and attached to the support 4 l, replacing the angles 45. However, as the more recent trend is toward the employment of metal shells as contrasted with glass envelopes, detailed representation of construction suitable for attachment to glass envelopes is omitted.

About the support or frame 4% and the base plate 29 there are stretched electrically conducting means which appear as individual strands 5i (Fig. 2) when viewed from the electron beam source. Anixed to the face of the target backing 29 against which the electron beam is adapted to impinge is a pair of insulating spacer elements respectively designated by the numerals 53 and 55 (Fig. 3) These spacers, as well as the translucent base plate 29 may comprise a bore silicate glass having an extremel low coefficient of expansion. Inorganic vitreous cement having the characteristic of minimum release of gas during bakeout of the tube, such as, for example, a potassium silicate compound manufactured under the trade name Kasil, is suitable for securing the spacer elements to the glass backing. The cement may be used as supplied or mixed with a glass frit.

Slots'li'l are preferably uniformly disposed in each of the spacer elements 53 and 55 to accommodate the strand conductors ii. The slots 5! in spacer element 55 are alined with the slots in spacer element 53 so that the conducting strands 5| present the mutually parallel arrangement shown in Fig. 2. It is to be understood, however, that the spacing between slots may be graduated to compensate for deviations in the angle of incidence of thebeam between the axis and the the base plate 29.

edges of the target. Accurate slotting of the glass spacer elements may be accomplished by either abrasive or photo etching processes carried out in conventional manner. The spacer elements provide the dual functions of alining and supporting in substantially coplanar relation the strands 5| at a uniform distance from the face of the target backing 2B. The spacing between adjacent slots 51 is substantially equal to the width of a single picture element, which is also approximately the diameter of the scanning beam as it approaches the plane of the strands. For best results (although this is not critical) the conducting strands 5| are spaced from the face of the target backing 29 which is impacted by the beam a distance approximately ten times the spacing between adjacent slots or strands 5|. This enables focusing of the scanning beam to a substantially linear trace having, of course, some width, which in actual practice is less than the dimension of a single phosphor area as impacted on the face of the target backing 29.

A feature of the present invention is the structure provided for mounting the target backing plate 29 Within the envelope 5. This may be appreciated when it is realized that preparation or bakeout of the tube during evacuation requires that the various electrodes mounted within the envelope 5 be exposed to ambient temperatures somewhere in the region of 400 centigrade. Since it is desired that a substantially uniform tension be imposed on each of the conducting strands 5| and since the coefficients of expansion, for example, of the metal frame 4| (which may comprise 430 modified steel, brass or other material), the conducting strands 5! (either stainless steel, nickel wire or the like), and the target backing 29 are more than likely all different, the problems encountered in assuring a taut state in the conducting strands 5| subsequent to the period when the tube is baked become apparent. It should likewise be appreciated that any holes placed in the target backing 29 for purposes of mounting establish local stresses in the glass plate and encourage fracture thereof. Thus, as is best shown in Figs. 4 and 5, this invention contemplates attachment of the backing plate 29 to the frame 4! by wrapping or winding the conducting strands 5| in continuous loop fashion about the vertical arms of the frame 4| and This procedure may be expedited by employing a jig to revolve the plate 29 relative to the wire being wrapped thereabout. However, in order to provide electrical isolation between the vertical arms of the frame 4| and the conducting strands 5|, insulators 6|, which may comprise glass ribbon or mica sheets or layers, are positioned adjacent to the arms of the frame 4| thereby to separate the conducting strands 5| from these arms.

After the winding operation has been completed insulating cement such as that manufactured under the trade name Insa-lute, having a characteristic of minimum release of gas during bakeout of the tube, is brushed or daubed onto the conducting strands El and vertical arms of the frame 4| to provide insulating mounds 63 which suitably cement themselves into slight recesses in the vertical arms of the frame 4|. Preferably the particular mixture of Insa-lute selected should have a coefl'icient of expansion similar to that of the frame material to prevent cracking during tube bakeout.

The electrode structure is then baked at a moderate temperature to permit the Insa-lute mounds 63 to set. Next, the portions of the conducting strands 5| extending between the Insa-lute mounds 63 are removed to provide an unobstructed window area behind the viewing area 31 of the tube.

In order that each pair of adjacent strands 5| may serve the function of an electrical lens to focus the beam into a substantially linear trace on the target backing 29 and simultaneously to provide structure for deflecting the focused trace from one phosphor area to another, terminal means are provided for connecting alternate strands 5| into two separate sets of conductors. One suitable structure for accomplishing this is shown in Figs. 4 and 5, where a conducting bar 65 is disposed adjacent to each of the Insa-lute mounds 63 respectively to contact alternate extremities of the conducting strands 5|. The extremities which are not to be contacted may be clipped off adjacent to the mounds 63 and the conducting bar 65 is then spot-welded to the protruding extremities of the strands 5| The relative positions of the conducting strands 5| and the red, green, and blue phosphor strips which are applied to the face of the target backing 29 impacted by the electron scanning beam is shown in Fig. 6. Such a preferred arrangement of the different colored phosphors comprises alternate red and blue strips with a half-width strip of green interposed between the red and blue strips, thereby providing overall equal areas of red, green and blue on the target area defined by the spacer elements. Likewise, it should be noted that a substantially equal area of each color is disposed between adjacent strands 5|, any other arrangement of the different color phosphors being subject only to this requirement. Thus, when like potentials (relative to the beam source) are applied to the individual strands shown in front of the red and blue strips, the beam will impinge upon the green strip; it being focused into a substantially linear trace by the electrical lenses formed between the conducting strands and the phosphor coated target area. In order to insure that the target presents a uniform potential distribution to the conducting strands, a thin layer of aluminum may be sputtered onto the phosphor strips to cover this area evenly and provide a convenient means of applying potential to the target relative to the electron beam source. Such an arrangement is described in United States patent application entitled Electrode Structure, Serial No. 307,436, filed concurrently with this application by the same inventor.

On the other hand, when different potentials relative to the electron beam source are applied to adjacent conducting strands 5| the beam is deflected into the red or blue region depending upon which set of strands 5| is more positive. In this latter situation the beam is still focused to a substantially linear trace by means of the electron lens established between the plane of the conducting strands 5| and the aluminum film. Thus, the angle of incidence of the electron beam may be altered as desired and the beam may be caused to impact the phosphor coated target to provide complete color reproduction. This is true regardless of whether the beam is caused to scan longitudinally or transversely of the phosphor strips. By way of A! are inserted, vided in-the form of insulating bushings and example, thGrSGCOIId anode s2! and. the electrode structure of the-instant invention may be maintained 3 to 4 kilovolts above the cathode l1 ode. The. application of -500 to 700 volts between the sets of conducting strands will. then serve to deflect the beam traceas herein outlined.

The electrode structure of the present invention as now described is ready for mounting within the evacuated envelope l5. As has been mentioned the angles 45 secured along the internal periphery of the envelope are provided for this purpose and the bolts or rivets proper insulation being promica spacers as described to insure electrical isolation between the envelope and the grid frame 4|. Next, the viewing end 3? of the tube is secured in place and the tube is then subjected to the evacuation and bakeout processes.

In connection-with these processes it will be remembered that the translucent base plate 29 is comprised of glass secured to a metal frame by means of metal conducting strands 5! partially surrounding the frame and glass target 29. Consequently, when the tube is subjected to temperatures in the neighborhood of 400 C. the metal parts, as-well as the glass, will expand. Therefore, *the problems of retaining accuracy of alinement in the electrode structure, as well as preventing fracture in the glass target, are presented.

The metal employed'for the frame or support 4| may have a coefficient of expansion greater than that of the strand wires 5!, for expansion'in the crossbars ll (Fig. 2) of the frame 4| during 'periods of elevated temperature will permit the strands to slacken- Among suitable materials for the conducting strandsfii are nickel and stainless steel. Preferably, the diameter of the conducting strands 51' is reduced to aminimum in order that'the grid structure may interceptas few electrons as possible.

When the tube is cooled following the bake-out process, the strands contract to provide an electrode structure wherein they are firmly secured in position under a certain degree of tension. The

amount of tension, of course, varies depending upon the tube dimensions and the particular metals employed as the frame and strands. By way of example, however, it has been found that the tension on the conductingstrands 5 E is in the neighborhood of-fifty thousand (50,000) lbs; per square inch fora conventional size tube, or, with 6 mil wire, about 2 lb; per strand. This imposes sufficient tension on the strands to bring the vibrational frequencies above those normally transmitted by the mountings, thereby preventing color distortions produced by changing spacings in the electrode structure. Owing to the structure herein described a substantially uniform tension is imposed on the conducting strands, thereby resulting in an accurate alinement of the strands in substantially coplanar relation.

Figs. 7 and 8 show a modified type electrode structure in accordance with the present invention employing a two-section frame comprising continuous loops or rectangular forms (similar to frame ill in Fig. 2) shown in cross section in Fig. '7 as the members 4! and 15 respectively. The continuous section member 4| is disposed adjacent-to the side of the target backing 29 which facesthe viewing end-310i the tube. A

phosphor coating 11 preferably in accordance with the showing of Fig. 6 is deposited on the opposite side of the target backing-Z9 between glass spacer elements 53 (only one of which is shown) in the manner of Fig. 3. A recess 19 may be formed in the section M along the longitudinal dimension thereof to receive vitreous cement such as Insa-lute in the form of the mound 63' which serves to retain the strands 5! in attachment with but electrically isolated from the section I. The glass spacer elements 53 are accurately notched or slotted in the manner hereinbefore described as shown in Fig. 4 and also, if desired, the edges of the backing plate 20 maybe provided with slots at each adapted to receive an individual conducting strand iii. However, the accuracy of alinement of the strands is dependent upon the slots in the spacer elements 53' and, accordingly, the slots 5! in the backing plate 29' merely serve as additional guiding means for the strands 5 i The conducting strands may conveniently be wound about the structure described, with specifically designated-alternate strands 85, 81, 89, etc., being wound in continuous loop fashion about the section s1, target backing 29 and spacer elements 53'. Subsequently, Insa-lute to comprise a mound ss' is brushed or daubed onto the strandsbi to fill the recess i9 and thus pro vide for attachment of the strands 85, 81, 89 etc., to the section ti. Similarly, as with the structure of Fig. 3 the portions of the strands 5i" (speific strands 85, 3'1, 39, etc.) extending between the Insa-lute mounds t3 areremoved thus providing a viewing area or window disposed opposite the viewing end 3'! of the tube.

One set of alternate conductors is thu in contact with the frame t! and a single connection to the frame wiil provide for the application of substantially uniform potential to the strands, '85, 8f, 89, etc.

The second set of conducting strands comprising those strands specifically labelled 9|, 93, 95, etc, in Fig. 8, is formed in the same manner as the'first set. A layer of glass ribbon or mica insulation 6! is placed between the frame sections ii and 15 to insure electrical isolation therebetween. A recess'tl may be provided in the frame section l5 so that the alternate strands Qi, E53, 95, etc. may be set in an Insa-lute mound E3 deposited over these conductors to fill the recess 91. After the Insa-lute has set, the portions of these conducting strands extending between the Insa-lute mounds 03" (only one of which is shown) are removed to provide a direct light path through the target backing 29 and the viewing end H of the tube. A connection is secured at any position along the frame section 15 to provide for the application of potential to this set of conducting strands thereby completing the electrode structure and providing for the applica-tionof like or uniike potentials to the frame sections ii and is relative to the electron beam source.

The structure shown in Figs. 7 and 8 functions in the manner of the structure of the previous figures to maintain tension in the conducting strands 5| following the bake-cut process.

Minimum stress is present in the target backing 29 due to the'manncr in which the remaining structure is secured thereto. Either or both of the frame sections 4! and "I5 may'be'provided with lugs similar to those designated as'S in Fig.

-2 to mount the electrode structure within and in electrical isolation from the evacuated envelope i5 through the employment of similar angles, bolts, or rivets and bushings, in the manner-hereinbefore described. Breakage of the strands during the tube preparation, is avoided since the coelficient of expansion of the material employed for the frame sections 4i and .75 may be higher or at least in the neighborhood of that of the strands 5i. It should further be noted that any distortion established in one frame section will not be transmitted to the other section. Also individual elements may expand or contract without necessarily influencing other elements of the electrode structure.

Figs. 9 through 11 show a similar embodiment of the present invention wherein hooks are employed to serve as the means for attachment of the conducting strands with the frame sections. The first frame section comprises the continuous loop or rectangular form 4|" positioned adjacent to a surface of the target backing 29". In the showing of Fig. 9 a pair of strips 42 (only one of which is visible) is secured respectively to opposite reaches of the frame section 4 l and each strip is provided with a plurality of depending posts or hooks 42'. If desired the strips 42 may be eliminated and the hooks 42' may be integral portions of the frame section 4|". Glass spacers 55' are provided with slots in the manner of the spacers 55 shown in Fig. 4 and are secured to the translucent base plate or target backing 29" in the manher of the showing of Fig. 2. Conducting strands generally designated as 5| are wound about the spacer elements 55', the target backing 29" and looped over the hooks 42 to form a continuous conducting means comprising the set of strands specifically designated as IUI, I03, I05, etc. shown in Fig. 11. This procedure is easily accomplished in a jig wherein motion of an oscillating character is imparted to the target backing and first frame section relative to the conducting strands being wound therein. The specific strands IUI, I83, H15, etc. constitute alternate strands as viewed from the electron beam source wherein the grid structure presents the appearance of that shown in Fig. 2. The second frame section comprises the continuous loop or rectangular form 15' having welded or otherwise secured thereto a pair of strips 15 (only one of which is visible) each provided with a plurality of depending posts or hooks 16 positioned respectively intermediate the hooks 42'. In similar fashion further conducting means comprising the strands specifically designated in Fig. 11 as Hi I I3, etc. are wound in continuous fashion about the target backing 29", the spacer elements 55 and looped over the hooks 16 to form a second set of continuous conducting means. Thus the frame sections 4|" and 15 serve as connections for the application of like or unlike potentials to the first and second set of conducting means thereby permitting beam focusing and deflection under the control of the conducting means in the manner hereinbefore set forth.

Again the electrode structure disclosed in Figs. 9 through 11 functions in a similar manner to the previously described electrode structures with a minimum of stresses being established in the glass backing plate 29" due to the manner in which this plate is supported and secured to the remaining portion of the electrode structure.

What is claimed is:

1. Electrode structure comprising a light transmissive base plate, a grid frame positioned adjacent to one face of the base plate, spacer elements secured to an opposite face of the base plate, and electrically conducting strands strung between opposed extremities of the frame via the spacer elements. v

2. Electrode structure comprising a light transmissive base plate, grid frame means disposed adjacent to a face of the base plate, a pair of slotted spacer elements secured to an opposite face of the base plate with slots in one element being in substantially respective alinement with slots in the other element, electrically conducting strands extending between a pair of opposed extremities of the frame means via the slots in the spacer elements, and connections on the conducting strands adapted for the application of potential thereto.

3. Electrode structure comprising a light transmissive base plate, frame means having at least a pair of opposed reaches disposed in juxtaposition with a surface of the base plate, spacer elements secured to an opposite surface of the base plate in substantially mutually parallel relationship and located between said reaches, said spacer elements having slots transversely thereof with the slots of the elements being substantially in respective alinement, electrically conducting strands anchored along one of said reaches and extending over an edge of the base plate, through the alined slots in the spacer elements, over an opposed edge of the base plate, and into anchored positions along the other of said reaches, and connections for applying potentials to the conducting means.

4. Electrode structure comprising a light transmissive base plate, frame means having at least a pair of reaches disposed in juxtaposition with a surface of the base plate, a pair of spacer elements affixed to a surface of the base plate 0pposed to said first mentioned surface in substantially parallel relationship one with the other, each of said spacer elements having slots transversely thereof with the slots in one element being respectively alined with the slots in the other element, electrically conducting strands secured at spaced intervals along one of said reaches and extending over an edge of the base plate, respectively through alined slots in each spacer element, over an edge of the base plate opposed to said first mentioned edge, and into spaced attachment along the other of said reaches, and connections for applying potentials to the conducting strands.

5. Electrode structure comprising in combination a light transmissive base plate, frame means having at least a pair of spaced reaches, said reaches being substantially parallel and coplanar, said frame means being juxtaposed with the base plate along a surface thereof, a pair of spacer elements secured to the base plate along a surface thereof opposed to said first mentioned surface, said spacer elements being substantially parallel to each other and to said reaches, electrically conducting strands, means for anchoring the electricallyconducting strands at spaced intervals along one of said reaches; said electric-ally conducting strands extending from said one reach, over an edge of the base plate, respectively in contact with each spacer element, and over an edge of the base plate opposed to said first mentioned edge, means for anchoring the strands at spaced intervals along the other of said reaches, and connections for applying different potentialsto adjacent strands.

6. Electrode structure comprising a light transmissive base plate, grid frame means positioned adjacent to a face of the base plate, a pair of separated spacer elements affixed to a face of the base plate opposed to said first mentioned face, each of said spacer elements having a plurality of slots 1 1 transversely thereof with the slots in one of said spacer elements being respectively in alinement with the slots in the other of said spacer elements,

electrically conducting strands anchored to opposed portions of the grid frame means and extending over opposed edges of the base plate, respectively through alined slots in said spacer elements, and spaced from said second mentioned face of the base member by the spacer elements, and connections for applying different potentials to adjacent strands.

'7. Electrode structure comprising a light transmissive base plate, grid frame means positioned adjacent to one face of the base plate, spacer elements secured to an opposite face of the base plate, electrically conducting strands strung between opposed extremities of the frame means via the spacer elements, and terminal connections adapted for the application of potential to the electrically conducting strands.

8. Electrode structure comprising a light transmissive base plate, grid frame sections disposed adjacent to a face of the base plate, insulating means disposed between said sections, spacer elements each having a plurality of slots secured to an opposite face of the base plate with the slots of the elements being in substantially respective alinement, electrically conducting strands extending between opposed extremities of each of the frame sections via the slots in the spacer elements, and connections on the conducting strands adapted for the application of potential thereto.

9. Electrode structure comprising a light transmissive base plate, frame means having at least a pair of opposed reaches disposed in juxtaposition with a surface of the base plate, spacer elements secured to an opposite surface of the base plate in substantially mutually parallel relationship and located between said reaches, said spacer elements having slots transversely thereof with the slots of the elements being substantially in alinement, phosphor strips capable upon excitation of producing different colored light deployed in cyclically repeating array on said opposite surface of the base plate between said spacer elements, electrically conducting means anchored along one of said reaches and extending under tension over an edge of the base plate, through the alined slots in the spacer elements, over an opposed edge of the base plate to terminate in anchored positions along the other of said reaches to secure the base plate to the frame means, and connections for applying potential to the conducting means.

10. Electrode structure comprising a light transmissive base plate, grid frame means having a coefficient of expansion greater than that of the base plate positioned adjacent to a face of the base plate, a pair of spacer elements having a coefiicient of expansion of the order of that of the base plate afiixed in separated positions to a face of the base plate opposed to said first mentioned face, each of said spacer elements having a plurality of slots transversely thereof with the slots in one of said spacer elements being respectively in alinement with the slots in the other of said spacer elements, electrically conducting strands having a coefficient of expansion less than that of the grid frame means anchored to opposed portions of the grid frame means and extending over opposed edges of the base plate, respectively through alined slots in said spacer elements, and spaced from said second mentioned face of the base plate by the spacer elements, and connections for applying different potentials to adjacent strands.

11. Electrode structure comprising a light transmissive base plate, a pair of frame sections each having at least a pair of reaches disposed in juxtaposition with a surface of the base plate, insulating means disposed between said sections, a pair of spacer elements affixed to a surface of the base plate opposed to said first mentioned surface in substantially parallel relationship one with the other, each of said spacer elements having slots transversely thereof with the slots in one element being respectively alined with the slots in the other element, electrically conducting strands secured at spaced intervals along one of the reaches of one section and extending over an edge of the base plate, respectively through alternate slots in the spacer elements, over an edge of the base plate opposed to said first mentioned edge, and into spaced attachment along the other of the reaches of said one section to comprise a first set of conducting means, further electrically conducting strands secured at spaced intervals along one of the reaches of the other frame section and extending over an edge of the base plate, respectively through slots adjacent to said alternate slots, over an edge of the base plate opposed to said first mentioned edge, and into spaced attachment along the other of the reaches of said other section to comprise a second set of conducting means, and connections for applying potentials to the sets of conducting means.

12. Electrode structure comprising in combination a light transmissive base plate, a pair of frame means each having at least a pair of spaced reaches, the reaches of each frame means being substantially parallel and coplanar, one of said frame means being juxtaposed with the base plate along a surface thereof, the other of said frame means being juxtaposed with said one frame means, insulating means interposed between said one and said other frame means, a pair of spacer elements secured to the base plate along a surface thereof opposed to said first mentioned surface,

said spacer elements being substantially parallel to each other and to said reaches, each of said spacer elements having a plurality of slots transversely thereof with the slots in one element being respectively alined with the slots in the other element, two sets of electrically conducting strands, means for anchoring each of the sets of electrically conducting strands respectively at spaced intervals along one of the reaches of each frame means, said electrically conducting strands extending from said reaches, over an edge of the base plate, respectively through alternate slots in the spacer elements, over an edge of the base plate opposed to said first mentioned edge, means for anchoring the strands of each set respectively at spaced intervals along the other of the reaches of each frame means, and connections for applying different potentials to adjacent strands.

13. Electrode structure comprising a light transmissive base plate, a grid frame having a pair of sections with one section being positioned adjacent to one face of the base plate and the other section being positioned adjacent to said one section, insulating means disposed between said sections, spacer elements secured to an opposite face of the base plate, two sets of electrically conducting strands'respectively strung between opposed extremities of the frame sections via the spacer elements, and terminal connections for each of said sets.

14. Electrode structure comprising a light transmissive base plate, grid frame means disposed adjacent to a face of the base plate, slotted spacer elements secured to an opposite face of the base plate with the slots in substantially respective alinement, electrically conducting means extending between opposed portions of the frame means via the slots in the spacer elements, and connections on the conducting means adapted for the application of potential thereto.

15. Electrode structure comprising a light transmissive base plate, a pair of frame sections each having at least a pair of opposed reaches disposed in juxtaposition with a surface of the base plate, insulating means interposed between the sections, spacer elements secured to an opposite surface of the base plate in substantially mutually parallel relationship and located between said reaches, said spacer elements having slots transversely thereof with the slots of the elements being substantially in alinement, electrically conducting means anchored along one of the reaches of one section and extending over an edge of the base plate, through alternate alined slots in the spacer elements, over an opposed edge of the base plate, and into anchored positions along the other of the reaches of said one section to comprise a first set of conducting means, further electrically conducting strands anchored along one of the reaches of the other frame sectlon and extending over an edge of the base plate, through slots respectively adjacent to said alternate slots, over an opposed edge of the base plate, and into anchored positions along the other of the reaches of said other section to comprise a second set of conducting means, and connections for applying potentials to the first and second sets of conducting means.

16. Electrode structure comprising alight transmissive base plate, frame means having at least a pair of parallel reaches disposed in juxtaposition with a surface of the base plate, a pair of spacer elements aflixed to a surface of the base plate opposed to said first mentioned surface in substantially parallel relationship with said reaches, each of said spacer elements having slots transversely thereof with the slots in one element being respectively alined with the slots in the other element, electrically conducting strands, means for securing the electrically conducting strands at spaced intervals along one of said reaches, said electrically conducting strands extending over an edge of the base plate, respectively through alined slots in each spacer element, over an edge of the base plate opposed to said first mentioned edge, and into spaced positions along the other of said reaches, means for securing the electrically conducting strands to said other reach in said positions, and connections for applying potentials to the conducting strands.

17. Electrode structure comprising in combination a light transmissive base plate, frame means having at least a pair of spaced reaches, said reaches being substantially parallel and'coplanar, said frame means being juxtaposed with the base plate along a surface thereof, a pair of spacer elements secured to the base plate along a surface thereof opposed to said first mentioned surface, said spacer elements being substantially parallel to each other and to said reaches, each of said spacer elements having a plurality of slots transversely thereof with the slots in one element being respectively alined with the slots in the other element, electrically conducting strands, cantilever means for anchoring the electrically conducting strands at spaced intervals along one of said reaches, said electrically conducting strands extending back and forth from said one reach, over an edge of the base plate, respectively through alined slots in each spacer element, over an edge of the base plate opposed to said first mentioned edge, further cantilever means for anchoring the strands at spaced intervals along the other of said reaches, and connections for applyin potential to the electrically conducting strands.

18. Electrode structure comprising a light transmissive base plate, grid frame means positioned adjacent to a face of the base plate, a pair of spacer elements afiixed in separated positions to a face of the base plate opposed to said first mentioned face, each of said spacer elements having a plurality of slots transversely thereof with the slots in one of said spacer elements being respectively in alinement with the slots in the other of said spacer elements, a plurality of different light producing phosphor strip coatings disposed on the base plate between said spacer elements in cyclically repeating array with the edges of the coatings being substantially parallel with the edges of said slots, electrically conducting strands anchored to opposed portions of the grid frame means and extending under tension over opposed edges of the base plate, respectively through alined slots in said spacer elements, and spaced from said second mentioned face of the base plate by the spacer elements to secure the base plate to the grid frame means, and connections for applying different potentials to adjacent strands.

References Cited in the file 0f this patent 

